Amide-ester copolymers and process for the preparation thereof

ABSTRACT

Copolymers comprising amide units and ester units are prepared by melt phase interchange of diaryl esters of dicarboxylic acids and diamines with dihydric alcohols and diesters of aromatic dicarboxylic acids. The products are tough resins, useful per se as molding compounds, and to compatibilize and toughen other thermoplastic polymers.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of Ser. No. 07/506,915 filed on Apr. 9, 1990, nowabandoned, which is a continuation of Ser. No. 07/117,245 filed on Nov.4, 19987 now abandoned.

This application is related to the following commonly assignedapplication

    ______________________________________                                        SERIAL                                                                        NO.     FIL-                                                                  (ATTY'S ING     APPLI-       STA-                                             DOCKET) DATE    TITLE        CANTS     TUS                                    ______________________________________                                        (337,2064)                                                                            now     COPOLYMERS   D. C. Clagett                                                                           Pend-                                  U.S. Ser.                                                                             aband-  AND          D. W. Fox ing                                    No.     oned,   PROCESS FOR  L. M. Maresca                                    07/117,250      FOR THE      S. J. Shafer                                                     PREPARATION                                                                   THEREOF                                                       ______________________________________                                    

FIELD OF THE INVENTION

The present invention relates to copolymer resins, thermoplasticcompositions comprising them, and processes useful in their preparation.More particularly, it is concerned with copolymers comprising amideunits and ester units, molding compositions comprising such copolymersand a melt phase process for their production by interchange of diarylesters with diamines and dihydric alcohols.

BACKGROUND OF THE INVENTION

Blends of polyamides with polycarbonates, poly(ester carbonates) andpolyarylates are known to exhibit desirable properties includingexcellent solvent resistance, ductility, hydrolytic stability andresistance to brittle failure when molded into articles. See, forexample, the copending, commonly assigned U.S. patent application of L.M. Maresca, D. C. Clagett and U. S. Wascher, Ser. No. 812,433 filed Dec.23, 1985 now abandoned, and U.S. Pat. No. 4,798,874, which is acontinuation-in-part of Ser. No. 07/812,433. Novel polyamide-polyarylatecopolymers have been prepared which have excellent and improved physicaland mechanical properties, and good chemical resistance and barrierproperties, and these are the subject matter of commonly assignedcopending application Ser. No. 07/117,250, now abandoned. Suchcopolymers are prepared in a melt polymerization process. Themicrostructure of the polymer can be controlled by running the processin one or two steps. A wide variety of diamines, diphenols and diacidesters can be used in the process in both steps. If, for example, apolyamide polyarylate block copolymer is desired, a two step process isused. In the first step, for example, diphenyl iso/terephthalate isreacted with a diamine in the melt at, for example, 120° C.-280° C., toproduce amide units. If a diphenol such as bisphenol-A and diphenyliso/terephthalate is added in a second step and the temperature of 230°C.-320° C. is used arlyate units will then be smoothly produced atreduced pressures as byproduct phenol is removed. Although Fox andShafer, U.S. Pat. No. 4,567,249, disclose the melt preparation ofpolyamides by amine-ester interchange, there is no hint of suggestion inthat patent to employ the process employing both an amine on the onehand, and a dihydric phenol on the other. It has now been found thatamide-ester copolymers, including random copolymers, block copolymersand alternating copolymers, can be synthesized by a melt polymerizationprocess. If carried out stepwise, in one step a polyamide block can beformed by the reaction of a diamine with a diaryl ester, e.g., diphenyliso/terephthalate at temperatures ranging from about 120° C. to about280° C. In a second step, a diol such as ethylene glycol, or1,4-butanediol can be used in the reaction along with diacid ester toform the polyester at similar temperatures i.e., more moderate thanrequired to make the polyarylate blocks. The new materials, which can bemade from a wide variety of diamines, diols and diacid esters, haveexcellent mechanical and physical properties good chemical resistanceand barrier properties.

SUMMARY OF THE INVENTION

According to the present invention, there are provided block copolymersof the general formula ##STR1## wherein units A comprise from about 1 toabout 99 percent by weight of said copolymer and units B comprise fromabout 99 to about 1 percent by weight of said copolymer, where E isselected from divalent alkyl, aryl, cycloalkyl, arylalkyl and alkylarylgroups of from 1 to 30 carbon atoms or a mixture of any of theforegoing, optionally substituted with at least one chlorine, bromine,fluorine, nitro, nitrile, alkyl of from 1 to 6 carbon atoms, alkoxy offrom 1 to 6 carbon atoms or aryl of from 6 to 20 carbon atoms; G is adivalent alkyl, aryl, cycloalkyl, arylalkyl or alkylaryl group of fromabout 2 to about 30 carbon atoms or a mixture of any of the foregoing,optionally interrupted with alkylene, arylene, carbonyl, ether, amino orsulfur-containing groups, optionally substituted with at least one ofchlorine, bromine, fluorine, nitro, nitrile, alkyl of from 1 to 6 carbonatoms, alkoxy of from 1 to 6 carbon atoms or aryl of from 6 to 20 carbonatoms; R is a divalent alkyl, cycloalkyl, aliphatic ether group of fromabout 2 to about 20 carbon atoms or a mixture of any of such groups; andAr is a divalent aromatic carbocyclic group, optionally substitued withat least one of chlorine, bromine, fluorine, nitro, nitrile, alkyl offrom 1 to 6 carbon atoms, alkoxy of from 1 to 6 carbon atoms aryl offrom 6 to 20 carbon atoms or a mixture of any of such groups, and x, yand z are each integers of from 1 to 100,000.

Preferred features of this aspect of the invention comprise a blockcopolymer as defined above wherein x and y are at least about 20.Preferred are copolymers wherein units of A comprise from about 20 toabout 80 percent by weight and units of B comprise from about 80 toabout 20 percent by weight of A and B combined, and especially preferredare copolymers wherein units of A comprise from about 40 to about 60percent by weight and units of B comprise from about 60 to about 40percent by weight of A and B combined.

Special mention is made of block copolymers as above defined wherein Eand Ar are ##STR2## G is divalent alkyl cycloalkyl, aryl or alkylaryl offrom about 2 to about 20 carbon atoms and R is ##STR3## wherein n is aninteger of from 2 to 6. Especially preferred are block copolymerswherein G is the residuum of ethylenediamine, trimethylenediamine,tetramethylenediamine, pentamethylenediamine,2-methylpentamethylenediamine, hexamethylenediamine, isomerictrimethylhexamethylenediamine, meta-xylylenediamine,para-xylylenediamine, 1,3-bis(aminomethyl)cyclohexane,1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane,1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, 1,4-piperazine,meta-phenylenediamine, para-phenylenediamine, bis(4-aminophenyl)methaneand the like or mixtures thereof.

Also provided by the present invention is a process to make thecopolymers above defined, said process comprising heating a mixture ofat least one diaryl ester of a dicarboxylic acid of the formula ##STR4##wherein the groups Ar³ represent the same or different aryl groups,optionally substituted with at least one of chlorine, bromine, fluorineor alkyl of from 1 to 6 carbon atoms and E is as above defined an amineof the formula

    R.sup.2 NH--G--NHR.sup.2

wherein G is as above defined and R² is hydrogen or alkyl of from 1 to10 carbon atoms, a dihydric alcohol of the formula

    HO--R--OH

wherein R is as above defined and at least one diester of a dicarboxylicacid of the formula ##STR5## wherein R³ is alkyl of from 1 to 12 carbonatoms or a group as defined for Ar³ above and Ar is as above definedoptionally in the presence of an effective amount of atransesterification catalyst and removing byproduct phenol, alcoholand/or water until formation of said copolymer is substantiallycomplete.

This process can be carried out in one or two stages depending on thestructure of the final copolymer desired. For example carrying out theprocess in one stage with all components mixed produces a randomcopolymer in which x, y and z have no consistently recurring values. If,however, essentially stoicimetric amounts of the diaryl ester of adicarboxylic acid and a diamine are reacted in the first stage followedby further polymerization in a second stage with essentiallystoichiometric amounts of a diol and a diaryl or dialkyl ester of anaromatic dicarboxylic acid then a block copolymer is formed where in xand y are consistantly greater than 15. In a third variation, if 2equivalents of a diaryl ester of a dicarboxylic acid is reacted with adiamine in step one then very small nylon oligomers are formed; additionof a diol in a second step results in the formation of an essentiallyalternating amide-ester copolymer. Values of x and y are essentiallyless then about 5. In all cases the combined concentrations of diaminesand diol must be essentially equal to the combined concentrations of thediaryl and/or dialky esters.

Preferably, the diaryl ester comprises a diaryl terephthalate, a diarylisophthalate, a diaryl adipate or a mixture thereof. Especiallypreferably, the diaryl ester will comprise diphenyl isophthalate,diphenyl terephthalate or diphenyl adipate. Preferably also, the diaminecomprises ethylenediamine, trimethylenediamine, tetramethylenediamine,pentamethylenediamine, 2-methylpentamethylenediamine,hexamethylenediamine, isomeric trimethylhexamethylenediamine,meta-xylylenediamine, para-xylylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis (aminomethyl)cyclohexane, 1,3 diaminocyclohexane,1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, 1,4-piperazine,meta-phenylenediamine, para-phenylenediamine, bis(4-aminophenyl)methaneand the like or mixtures thereof. Preferably the diester of the aromaticdicarboxylic acid will comprise a dialkyl or diaryl terephthalate, adialkyl or diaryl isophthalate or a mixture thereof. Special mention ismade of a process wherein the dihydric alcohol comprises ethyleneglycol, 1,4-butanediol, polybutylene glycol, 1,4-cyclohexanedimethanol,or a mixture of any of the foregoing.

Also among the preferred features of the invention are copolymersprepared in a melt phase process by the interchange of an excess of adiamine or diaryl ester to produce a polyamide having amine or esterterminal groups and further reacting the the polyamide with a dihydricalcohol and a diester of a dicarboxylic acid to form apolyamide-polyester block copolymer containing from about 1 to about 99percent by weight of polyamide segments and from about 99 to about 1percent by weight of polyester segments. In these, preferably, thediamine comprises a diprimary or disecondary amine.

The copolymers are thermoformable into shaped articles which are tough,thermally stable and resistant to chemicals and hydrolysis. They arealso useful as blending resins.

DETAILED DESCRIPTION OF THE INVENTION

As examples of diamines particularly suitable for use in preparing the Aunits can be mentioned diprimary and disecondary as well as mixedprimary and secondary diamines of the general formula above.Illustrative examples are ethylenediamine, trimethylenediamine,tetramethylenediamine, pentamethylenediamine, 2-methylpentamethylenediamine, hexamethylenediamine, isomeric trimethylhexamethylenediamine,meta-xylylenediamine, para-xylylene diamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis (aminomethyl)cyclohexane, 1,3-diaminocyclohexane,1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, 1,4-piperazine,meta-phenylenediamine, para-phenylenediamine, bis(4-aminophenyl)methaneand the like or mixtures thereof.

Illustratively useful diesters suitable as sources for structural unitsE are esters of dicarboxylic acids such as diphenylic esters derivedfrom phenolic compounds, e.g., a monohydric phenol, including phenolitself, and alkyl- or halo-substituted phenols, such as o-, m- andp-cresols, and o- and p-chlorophenol and the like, and a dicarboxylicacid, such as adipic, sebacic, glutaric, phthalic, terephthalic,isophthalic, naphthalene dicarboxylic, biphenyl dicarboxylic acid, andthe like. A preferred family of diesters comprises the diphenyl estersof terephthalic acid, isophthalic acid, and mixtures thereof.

With respect to the ester unit B, these are derived from an aliphatic,aliphatic ether or cycloaliphatic diols, or mixtures thereof, containingfrom 2 to about 10 carbon atoms and at least one aromatic dicarboxylicacid. Preferred polyester blocks are derived from an aliphatic diol andan aromatic dicarboxylic acid and have repeating units of the followinggeneral formula: ##STR6## wherein n is an integer of from 2 to 6. Themost preferred polyester blocks comprise poly(ethylene terephthalate) orpoly(1,4-butylene terephthalate).

Also contemplated herein are units of the above esters with minoramounts, e.g., from 0.5 to about 2 percent by weight, of units derivedfrom aliphatic acids and/or aliphatic polyols, to form copolyesters. Thealiphatic polyols include glycols, such as poly (ethylene glycol). Allsuch polyesters can be made following the teachings of, for example,U.S. Pat. Nos. 2,465,319 and 3,047,539.

The ester units that are derived from a cycloaliphatic diol and anaromatic and/or cycloaliphatic dicarboxylic acid are prepared, forexample, from reaction of either the cis-or trans-isomer (or mixturesthereof), of 1,4-cyclohexanedimethanol, with an aromatic dicarboxylicacid so as to produce an ester having units of the following formula:##STR7## wherein the cyclohexane ring is selected from the cis- andtrans-isomers thereof and Ar represents an aryl or substituted arylradical containing 6 to 20 carbon atoms and which is the decarboxylatedresidue derived from an aromatic dicarboxylic acid.

Examples of aromatic dicarboxylic acids represented by thedecarboxylated residue Ar are isophthalic or terephthalic acid,1,2-di(p-carboxyphenyl) ethane, 4,4'-dicarboxydiphenyl ether, etc., andmixtures of these. All of these acids contain at least one aromaticnucleus. Acids containing fused rings can also be present, such as in1,4- or 1,5-naphthalenedicarboxylic acids. The preferred dicarboxylicacids are terehthalic acid or a mixture of terephthalic and isophthalicacids.

Another preferred ester unit may be derived from the reaction of eitherthe cis- or trans-isomer (or a mixture thereof) of1,4-cyclohexanedimethanol with a mixture of isophthalic and terephthalicacids. Such an ester would have units of the formula: ##STR8##

Also included within this invention are polyesters derived fromaliphatic ether diols, for example, tetraethyleneoxy diol, and the samediesters of diacids.

In general, any diester of an aromatic dicarboxylic acid conventionallyused in the preparation of polyesters, may be used for the preparationof the polyester blocks described above. The esters of aromaticdicarboxylic acids which may be used include those of aliphatic-aromaticdicarboxylic acids, in addition to those of wholly aromatic dicarboxylicacids.

The diesters of dicarboxylic acids are represented by the generalformula: ##STR9## wherein R³ and Ar are as defined above, Ar being, forexample, phenylene, naphthylene, biphenylene, substituted phenylene,etc.; two or more aromatic groups connected through non-aromaticlinkages or a divalent aliphatic-aromatic hydrocarbon radical such as anarylalkyl or alkylaryl radical. For purposes of the present invention,R³ is an aliphatic or cycloaliphatic radical, such as methyl, ethyl,n-propyl, dodecyl, octadecyl or an aromatic radical such as phenylene,biphenylene, naphthylene, substituted phenylene, etc. Some nonlimitingexamples of suitable diesters of aromatic dicarboxylic acids which maybe used in preparing the ester units of the instant invention includedialkyl and diaryl esters of phthalic acid, isophthalic acid,terephthalic acid, homophthalic acid, o-, m-, and p-phenylenediaceticacid, and the polynuclear aromatic acids such as diphenyl dicarboxylicacid, and isomeric naphthalene dicarboxylic acids. The aromatics may besubstituted with inert groups such as bromine, chlorine, fluorine alkylof from 1 to 6 carbon atoms, alkoxy of from 1 to 6 carbon atoms, aryl offrom 6 to 20 carbon atoms, and the like. Of course, these esters may beused individually or as mixtures of two or more different acids.

If desired, a conventional esterification catalyst can be used.Preferred as catalysts suitable for this purpose are, for example,acetates, carboxylates, hydroxides, oxides, alcoholates or organiccomplex compounds of zinc, manganese, antimony, cobalt, lead, calciumand the alkali metals. Preferably, inorganic or organictitanium-containing catalysts will be used such as tetrabutyl titanateor tetraoctyl titanate. In general, from about 0.005 to about 2.0percent by weight of catalyst will be used, based on ester formingreactants. The alcoholic or phenolic byproducts can be removed, e.g., byvacuum devolatilization in the reactor or an extruder or a combinationof the two. Alternatively, the byproduct can be solvent-extracted, e.g.,with toluene. The resulting copolymer can be recovered in any convenientmanner, remaining, for example, as a residue after vacuumdevolatilization, or by precipitation from a solvent by means of anantisolvent, such as methanol.

The products of the process may be molded in any desired shape and areuseful as structural and engineering materials to replace metal parts,in automotive applications, electrical appliances, and in foodwrappings, as stand alone resins, in blends with other resins such aspolyesters, polyarylates and nylons and as tie resins to bond twodifferent resin layers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples illustrate the invention. They are not to beconstrued to limit the claims in any manner whatsoever.

EXAMPLE 1

A 4CV Helicone mixer was charge with 487.1 g (1.53 moles) of diphenylisophthalate and 174.3 g (1.50 moles) of hexamethylenediamine andblanketed with nitrogen. Agitation was started and the temperature wasraised to 180° C.-185° C. After 45 minutes at 180° C. to 185° C. thetemperature was lowered to 165° C. and 324.0 g (1.67 moles) of dimethylterephthalate, 251.0 g (2.79 moles) of 1,4-butanediol and 1.0 ml oftetraoctyl titanate were added. After 15 minutes methanol began todistill. The reaction temperature was increased to 200° C.-205° C. after75% of the theoretical amount of methanol distilled and 235° C. at 95%theoretical. A partial vacuum of 125 mm of Hg was applied to the systemand slowly decreased to full vacuum, less than 2 mm of Hg, over 1 hour.At full vacuum, the temperature was increased to 250° C.-255° C. andheld there for 2 to 2.5 hours. After breaking vacuum the block copolymerwas discharged from the reactor and allowed to cool to room temperature.The polymer extrudate was tough and opaque. Its instrinsic viscosity(IV), glass transition temperature (Tg) and melting point (Tm) are shownin Table 1.

EXAMPLES 2 AND 3

Example 1 was repeated and the resulting block copolymers were tough andhad the IVs, Tgs and Tms shown in Table 1.

                  TABLE 1                                                         ______________________________________                                        Example  IV.sup.1     Tg(°C.).sup.2                                                                   Tm(°C.).sup.2                           ______________________________________                                        1        0.77         118      219                                            2        0.76         115      218                                            3        0.69         115      218                                            ______________________________________                                         .sup.1 Intrinsic Viscosity, measured in phenol/tetrachloroethane (60/40)      at 23° C.                                                              .sup.2 Glass transition and melting temperatures, measured by differentia     scanning calorimetry.                                                    

EXAMPLE 4 AND 7

If the procedure of Example 1 is repeated, substituting for thehexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane,1,4-bis(aminomethyl)cyclohexane, meta-xylylenediamine or para-xylylenediamine, block copolymers according to this invention will be obtained.

EXAMPLE 8

If the procedure of Example 1 is repeated, substituting piperazine forhexamethylenediamine, a block copolymer product according to thisinvention will be obtained.

EXAMPLE 9

If the procedure of Example 1 is repeated, substituting diphenyl adipatefor diphenyl isophthalate in the first stage, a block copolymeraccording to the invention will be obtained.

EXAMPLE 10

If the procedure of Example 1 is repeated, substituting for the diphenylisophthalate in the first stage a 50--50 weight/weight mixture ofdiphenyl isophthalate and diphenyl terephthalate and dimethylisophthalate in the second stage, a block copolymer according to thisinvention will be obtained.

EXAMPLES 11-12

If the procedure of Example 1 is repeated, substituting, respectively,ethylene glycol or 1,4-cyclohexanedimethanol for the 1,4-butanediolemployed in the second stage, block copolymers in accordance with thisinvention will be obtained.

EXAMPLE 13

If the procedure of Example 1 is carried out in one stage, by adding allof the ingredients, including the catalyst, at once to the reactor, arandom amide-ester copolymer in accordance with this invention will beobtained.

EXAMPLE 14

The procedure of Example 1 is repeated except that 2 equivalents ofdiphenyl isophthalate is reacted with hexamethylenediamine in step 1.One equivalent of 1,4-butanediol is added in step 2. An essentiallyalternating amide ester copolymer in accordance with this invention isproduced.

The above-mentioned patents, patent applications and publications areincorporated herein by reference.

Many variations of this invention will suggest themselves to thoseskilled in this art in light of the above, detailed description. Forexample, instead of diphenyl isophthalate and diphenyl terephthalate,the following diaryl esters can be used, diphenyl adipate, diphenylsebacate, diphenyl glutarate, diphenyl naphthalene dicarboxylate,diphenyl biphenyl dicarboxylate, mixtures of any of the foregoing, andthe like. Instead of hexamethylenediamine and the other diamines used,the following may be substituted: ethylenediamine, trimethylenediamine,tetramethylenediamine, pentamethylenediamine,2-methylpentamethylenediamine, hexamethylenediamine, isomerictrimethylhexamethylenediamine, meta-xylylenediamine,para-xylylenediamine, 1,3-bis(aminomethyl) cyclohexane,1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane,1,4-bis(aminomethyl) cyclohexane, 1,3-diaminocyclohexane,1,4-diaminocylohexane, bis(4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, 1,4-piperazine,meta-phenylenediamine, para-phenylenediamine, bis(4-aminophenyl) methaneand the like or mixtures thereof. Instead of 1,4-butanediol, there canbe substituted ethylene glycol, 1,3-propanediol,1,4-cyclohexanedimethanol, polytetramethylene ether diol, mixtures ofany of the foregoing and the like. All such obvious variations arewithin the full intended scope of the appended claims.

We claim:
 1. An alternating copolymer of the formula: ##STR10## preparedby (a) reacting two equivalents of a diaryl ester of a dicarboxylic acidhaving the formula: ##STR11## with a diamine of the formula:

    R.sup.2 NH--G--NHR.sup.2

and then (b) reacting the product formed in (a) with a diol of theformula:

    HO--R--OH

to form the alternating amide-ester-ether copolymer, wherein units Acomprise from about 1 to about 99 percent by weight of said copolymerand units B comprise from about 99 to about 1 percent by weight of saidcopolymer, where E is a divalent aryl group unsubstituted or substitutedwith at least one chlorine, bromine, fluorine, nitro, nitrile, alkyl offrom 1 to 6 carbon atoms, alkoxy of from 1 to 6 carbon atoms or aryl offrom 6 to 20 carbon atoms, or a mixture of any of the foregoing; G is adivalent, aryl, or cycloalkyl group of from about 2 to about 30 carbonatoms or a mixture of any of the foregoing, or G is as defined and isinterrupted with alkylene, arylene, carbonyl, ether, amino or sulfurcontaining groups, unsubstituted or substituted with at least one ofchlorine, bromine, fluorine, nitro, nitrile, alkyl of from 1 to 6 carbonatoms, alkoxy of from 1 to 6 carbon atoms, or aryl of from 6 to 20carbon atoms, or a mixture of any of the foregoing; R is a divalentalkyl, cycloalkyl, or aliphatic ether group of from about 2 to about 20carbon atoms or a mixture of such groups; Ar³ is the same or differentaryl group or aryl group substituted with at least one of chlorine,bromine, fluorine, or alkyl of from 1 to 6 carbon atoms, and R² ishydrogen or an alkyl radical having from 1 to 10 carbon atoms; and x, yand z are integers of from 1 to 100,000.
 2. A copolymer as defined inclaim 1 wherein units of A comprise from about 20 to about 80 percent byweight and units of B comprise from about 80 to about 20 percent byweight of A and B combined.
 3. A copolymer as defined in claim 2 whereinunits of A comprise from about 40 to about 60 percent by weight andunits of B comprise from about 60 to about 40 percent by weight of A andB combined.
 4. A copolymer as defined in claim 1 wherein E is theresidue of a diacid selected from phthalic, terephthalic, isophthalic,naphthalene, biphenyl dicarboxylic acids or a mixture of any of theforegoing.
 5. A copolymer as defined in claim 1 wherein E is the residueof a diacid selected from phthalic, terephthalic, isophthalic,naphthalene, biphenyl dicarboxylic acids or other aromatic dicarboxylicacids.
 6. A copolymer as defined in claim 5 wherein E is ##STR12## R is##STR13## n is an integer of from 2 to
 6. 7. A copolymer as defined inclaim 1 wherein G is selected from meta-xylylenediamine,paraxylylenediamine, 1,3-bis(aminomethyl)cyclohexane,1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane,1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, 1,4-piperazine,meta-phenylenediamine, para-phenylenediamine, bis(4-aminophenyl)methane,or mixtures thereof.
 8. A copolymer as defined in claim 1 wherein R is aresiduum of a diol selected from ethylene glycol, propanediol,1,4-butanediol, polytetramethylene ether diol, 1,4-cyclohexanedimethanolor a mixture of any of the foregoing.
 9. A copolymer as defined in claim8 wherein R is a residuum of 1,4-butanediol.